Citrus australis

Microcitrus australis is a species of the genus Microcitrus in the rue family ( Rutaceae ). It is used as an ornamental and fruit trees.

Description

Appearance and leaf

Microcitrus australis grows as a tree with growth heights of 10-20 meters. The emerging Leittriebe grow straight with internodes of 1 to 1.5 cm long, the short side shoots are slightly zigzag, here the internodes are only 0.5 to 1 cm long. The branches are rectangular in cross section. The thorns are individually and 0.5 to 1 cm long, at the side shoots only 0.2 to 0.5 cm at the Leittrieben.

Young plants have only greatly reduced low- leaves, later develop small oblong to elliptical leaves, which gradually lead to the leaf shape of the adult plant. Their leaves are divided into leaf blade and petiole, between the two is a separating tissue. The 2-3 mm long petiole is hairy and flattened on the top. At higher branches of the leaf blades with a length of 3 to 4 cm and a width of 2 to 3 cm are obovate to almost the - heart-shaped. At weak side shoots, the leaves remain small with a length of 2 to 3 cm and a width of 1.2 to 1.8 cm, here they are rhombic in shape. The leaves are glabrous, sometimes sparsely ciliate at the leaf base. The leaf veins are visible, especially on the underside of leaves. On each side of the midrib branches from 12 to 15 leaf veins, which in turn branch out again.

Flower, fruit and seeds

The flowers appear singly in the leaf axils. The flowers are hermaphroditic radial symmetry and four - or fünfzählig with a diameter of 1 to 1.5 cm. The number of stamens is 16 to 20 The stamens are fused together.

The fruits are spherical with a diameter of 2.5 to 5 cm. They can, like other citrus fruits, divided into segments, there are six such segments exist. The segments are in turn made ​​of numerous juice sacs together, the shape of this juice sacs is characteristic: they are short-stalked to the outside wall of the fruit, cigar-shaped extending inwardly and terminating in a blunt and often irregularly shaped tip. On the outer wall of the fruit they are very light green, inside dyed to strong green. The individual juice sacs are 6 to 10 mm long and 2.5 to 3.5 mm wide; in the ripe fruit stick them all together easily. Their consistency is pretty solid - so they can be cut without their content expires. The content consists of acidic, green juice and numerous large, yellowish oil droplets. The flattened seed contains only one embryo.

Occurrence

Microcitrus australis from the north- eastern Australia. The type specimen was collected on the Moreton Bay.

Systematics and botanical history

The first description was in 1829 under the name ( basionym ) Limonia australis by Robert Mudie in The Picture of Australia, p 151 It was in 1915 under the name Microcitrus by Walter Tennyson Swingle australis in the Journal of the Washington Academy of Sciences, Volume 5, S. 572 placed in the new genus Microcitrus. Another synonym for Microcitrus australis ( Mudie ) Swingle is Citrus australis ( A.Cunn. Mudie ex ) Planch ..

The cleavage of the genus of Citrus Microcitrus causes the latter is no longer monophyletic. Recent work relating Microcitrus therefore again in the genus Citrus and rename the plant Citrus australis described here.